As the number of people who have email accounts continues to increase at a near exponential rate, so too does the number of unsolicited email messages received by the average person each day. Whether the unsolicited email messages originate from companies with which a particular end user has previously conducted business, or from companies that are generally unknown to the end user, the result is the same. That is, unsolicited messages frequently result in decreased end user productivity and increased transaction costs for the user or user's employer.